1. Field of the Invention
The invention relates to an apparatus for use in carrying out a physical and/or chemical process, in particular a heat exchanger.
2. Description of the Prior Art
The applicants' Dutch patent application No. 80 06161 describes a heat exchanger having a bundle of parallel vertical riser tubes which are mounted in header plates and open into a lower tank and an upper tank. A granular mass (i.e. a particle mass) is present which can be fluidized during operation to occupy at least the tubes by a liquid medium flowing upwardly through the tanks and riser tubes. In addition there is at least one return tube for returning the granular mass from the upper tank to the lower tank, having valve means which hinder the passage of the liquid medium through the return tube. The valve means disclosed consists of a lock arrangement for the granules in the return tube, comprising two valves which are connected to each other, and can be opened and closed alternately. In this apparatus the purpose is to return a surplus of granules from the upper tank to the lower tank in batches without carrying out liquid with them. The return tube may be mounted near to or among the riser tubes.
In this apparatus, velocities of the liquid medium in the riser tubes are permissible which cause the granular mass to be transported upwards. These higher velocities permit a more attractive configuration of the riser tube bundle, so that the whole apparatus can be made narrower. Another advantage is that the higher velocities which can be achieved in the riser tubes result in an enhanced scouring and cleaning action of the granules on the tube walls. This permits applications in systems using liquids which have a pronounced fouling action, for instance, applications in the food processing industry and especially with liquids from which proteins can be deposited on the tube wall.
In this specification, by apparatus for the operation of a physical and/or chemical process (e.g. a heat exchanger), it is intended to mean apparatus in which physical and/or chemical processes are carried out on a liquid by the addition or removal of heat through the tube walls.